The studies described in this proposal are designed to provide information about the molecular pathology of bacterial lipopolysaccharide (LPS)-induced hypotensive shock and disseminated intravascular coagulation (DIC). The major objective of this reseach is to evaluate the role of LPS interactions with hepatic macrophages (Kupffer cells) in the initiation of LPS-induced injury. To do this we will first standardize and optimize methods to explant hepatic macrophages and then study the effect of LPS on the biochemical properties of these cells. Specifically we will examine the effect of LPS on enzyme production and release, prostaglandins, toxic metabolites of oxygen and procoagulant activity of the hepatic macrophage. Thus we will determine if the hepatic macrophage, the principal cellular target of LPS in the host releases mediators capable of initiating LPS-induced shock and DIC. Supernatants from LPS treated hepatic macrophages will also be examined for mediators that interact with other host defense systems which may amplify the injurious effects of LPS; namely platelets, neutrophils, endothelial cells and heptocytes. Once the in vitro response of the hepatic macrophage to LPS is characterized we will evaluate the pathogenic significance of these changes by three distinct experimental strategies: (1) to determine if changes in hepatic macrophages detected in vitro occur in vivo in these cells following LPS injection; (2) to block the effect of a potential mediator by depletion or pharmacologic inhibition; and (3) to utilize the LPS-resistant mouse strain the C3H/HeJ.